USB: xhci: Add tests for TRB address translation.

It's not surprising that the transfer request buffer (TRB) physical to
virtual address translation function has bugs in it, since I wrote most of
it at 4am last October.  Add a test suite to check the TRB math.  This
runs at memory initialization time, and causes the driver to fail to load
if the TRB math fails.

Please excuse the excessively long lines in the test vectors; they can't
really be made shorter and still be readable.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 163 insertions, 2 deletions

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index fd05247..711dc55 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -859,6 +859,163 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 	xhci->page_shift = 0;
 }
 
+static int xhci_test_trb_in_td(struct xhci_hcd *xhci,
+		struct xhci_segment *input_seg,
+		union xhci_trb *start_trb,
+		union xhci_trb *end_trb,
+		dma_addr_t input_dma,
+		struct xhci_segment *result_seg,
+		char *test_name, int test_number)
+{
+	unsigned long long start_dma;
+	unsigned long long end_dma;
+	struct xhci_segment *seg;
+
+	start_dma = xhci_trb_virt_to_dma(input_seg, start_trb);
+	end_dma = xhci_trb_virt_to_dma(input_seg, end_trb);
+
+	seg = trb_in_td(input_seg, start_trb, end_trb, input_dma);
+	if (seg != result_seg) {
+		xhci_warn(xhci, "WARN: %s TRB math test %d failed!\n",
+				test_name, test_number);
+		xhci_warn(xhci, "Tested TRB math w/ seg %p and "
+				"input DMA 0x%llx\n",
+				input_seg,
+				(unsigned long long) input_dma);
+		xhci_warn(xhci, "starting TRB %p (0x%llx DMA), "
+				"ending TRB %p (0x%llx DMA)\n",
+				start_trb, start_dma,
+				end_trb, end_dma);
+		xhci_warn(xhci, "Expected seg %p, got seg %p\n",
+				result_seg, seg);
+		return -1;
+	}
+	return 0;
+}
+
+/* TRB math checks for xhci_trb_in_td(), using the command and event rings. */
+static int xhci_check_trb_in_td_math(struct xhci_hcd *xhci, gfp_t mem_flags)
+{
+	struct {
+		dma_addr_t		input_dma;
+		struct xhci_segment	*result_seg;
+	} simple_test_vector [] = {
+		/* A zeroed DMA field should fail */
+		{ 0, NULL },
+		/* One TRB before the ring start should fail */
+		{ xhci->event_ring->first_seg->dma - 16, NULL },
+		/* One byte before the ring start should fail */
+		{ xhci->event_ring->first_seg->dma - 1, NULL },
+		/* Starting TRB should succeed */
+		{ xhci->event_ring->first_seg->dma, xhci->event_ring->first_seg },
+		/* Ending TRB should succeed */
+		{ xhci->event_ring->first_seg->dma + (TRBS_PER_SEGMENT - 1)*16,
+			xhci->event_ring->first_seg },
+		/* One byte after the ring end should fail */
+		{ xhci->event_ring->first_seg->dma + (TRBS_PER_SEGMENT - 1)*16 + 1, NULL },
+		/* One TRB after the ring end should fail */
+		{ xhci->event_ring->first_seg->dma + (TRBS_PER_SEGMENT)*16, NULL },
+		/* An address of all ones should fail */
+		{ (dma_addr_t) (~0), NULL },
+	};
+	struct {
+		struct xhci_segment	*input_seg;
+		union xhci_trb		*start_trb;
+		union xhci_trb		*end_trb;
+		dma_addr_t		input_dma;
+		struct xhci_segment	*result_seg;
+	} complex_test_vector [] = {
+		/* Test feeding a valid DMA address from a different ring */
+		{	.input_seg = xhci->event_ring->first_seg,
+			.start_trb = xhci->event_ring->first_seg->trbs,
+			.end_trb = &xhci->event_ring->first_seg->trbs[TRBS_PER_SEGMENT - 1],
+			.input_dma = xhci->cmd_ring->first_seg->dma,
+			.result_seg = NULL,
+		},
+		/* Test feeding a valid end TRB from a different ring */
+		{	.input_seg = xhci->event_ring->first_seg,
+			.start_trb = xhci->event_ring->first_seg->trbs,
+			.end_trb = &xhci->cmd_ring->first_seg->trbs[TRBS_PER_SEGMENT - 1],
+			.input_dma = xhci->cmd_ring->first_seg->dma,
+			.result_seg = NULL,
+		},
+		/* Test feeding a valid start and end TRB from a different ring */
+		{	.input_seg = xhci->event_ring->first_seg,
+			.start_trb = xhci->cmd_ring->first_seg->trbs,
+			.end_trb = &xhci->cmd_ring->first_seg->trbs[TRBS_PER_SEGMENT - 1],
+			.input_dma = xhci->cmd_ring->first_seg->dma,
+			.result_seg = NULL,
+		},
+		/* TRB in this ring, but after this TD */
+		{	.input_seg = xhci->event_ring->first_seg,
+			.start_trb = &xhci->event_ring->first_seg->trbs[0],
+			.end_trb = &xhci->event_ring->first_seg->trbs[3],
+			.input_dma = xhci->event_ring->first_seg->dma + 4*16,
+			.result_seg = NULL,
+		},
+		/* TRB in this ring, but before this TD */
+		{	.input_seg = xhci->event_ring->first_seg,
+			.start_trb = &xhci->event_ring->first_seg->trbs[3],
+			.end_trb = &xhci->event_ring->first_seg->trbs[6],
+			.input_dma = xhci->event_ring->first_seg->dma + 2*16,
+			.result_seg = NULL,
+		},
+		/* TRB in this ring, but after this wrapped TD */
+		{	.input_seg = xhci->event_ring->first_seg,
+			.start_trb = &xhci->event_ring->first_seg->trbs[TRBS_PER_SEGMENT - 3],
+			.end_trb = &xhci->event_ring->first_seg->trbs[1],
+			.input_dma = xhci->event_ring->first_seg->dma + 2*16,
+			.result_seg = NULL,
+		},
+		/* TRB in this ring, but before this wrapped TD */
+		{	.input_seg = xhci->event_ring->first_seg,
+			.start_trb = &xhci->event_ring->first_seg->trbs[TRBS_PER_SEGMENT - 3],
+			.end_trb = &xhci->event_ring->first_seg->trbs[1],
+			.input_dma = xhci->event_ring->first_seg->dma + (TRBS_PER_SEGMENT - 4)*16,
+			.result_seg = NULL,
+		},
+		/* TRB not in this ring, and we have a wrapped TD */
+		{	.input_seg = xhci->event_ring->first_seg,
+			.start_trb = &xhci->event_ring->first_seg->trbs[TRBS_PER_SEGMENT - 3],
+			.end_trb = &xhci->event_ring->first_seg->trbs[1],
+			.input_dma = xhci->cmd_ring->first_seg->dma + 2*16,
+			.result_seg = NULL,
+		},
+	};
+
+	unsigned int num_tests;
+	int i, ret;
+
+	num_tests = sizeof(simple_test_vector) / sizeof(simple_test_vector[0]);
+	for (i = 0; i < num_tests; i++) {
+		ret = xhci_test_trb_in_td(xhci,
+				xhci->event_ring->first_seg,
+				xhci->event_ring->first_seg->trbs,
+				&xhci->event_ring->first_seg->trbs[TRBS_PER_SEGMENT - 1],
+				simple_test_vector[i].input_dma,
+				simple_test_vector[i].result_seg,
+				"Simple", i);
+		if (ret < 0)
+			return ret;
+	}
+
+	num_tests = sizeof(complex_test_vector) / sizeof(complex_test_vector[0]);
+	for (i = 0; i < num_tests; i++) {
+		ret = xhci_test_trb_in_td(xhci,
+				complex_test_vector[i].input_seg,
+				complex_test_vector[i].start_trb,
+				complex_test_vector[i].end_trb,
+				complex_test_vector[i].input_dma,
+				complex_test_vector[i].result_seg,
+				"Complex", i);
+		if (ret < 0)
+			return ret;
+	}
+	xhci_dbg(xhci, "TRB math tests passed.\n");
+	return 0;
+}
+
+
 int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 {
 	dma_addr_t	dma;
@@ -962,6 +1119,8 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 	xhci->event_ring = xhci_ring_alloc(xhci, ERST_NUM_SEGS, false, flags);
 	if (!xhci->event_ring)
 		goto fail;
+	if (xhci_check_trb_in_td_math(xhci, flags) < 0)
+		goto fail;
 
 	xhci->erst.entries = pci_alloc_consistent(to_pci_dev(dev),
 			sizeof(struct xhci_erst_entry)*ERST_NUM_SEGS, &dma);
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index aaed076..371ba42 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -987,8 +987,7 @@ static void handle_port_status(struct xhci_hcd *xhci,
  * TRB in this TD, this function returns that TRB's segment.  Otherwise it
  * returns 0.
  */
-static struct xhci_segment *trb_in_td(
-		struct xhci_segment *start_seg,
+struct xhci_segment *trb_in_td(struct xhci_segment *start_seg,
 		union xhci_trb	*start_trb,
 		union xhci_trb	*end_trb,
 		dma_addr_t	suspect_dma)
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index c92f841..3989aadc 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1268,6 +1268,9 @@ void xhci_reset_bandwidth(struct usb_hcd *hcd, struct usb_device *udev);
 
 /* xHCI ring, segment, TRB, and TD functions */
 dma_addr_t xhci_trb_virt_to_dma(struct xhci_segment *seg, union xhci_trb *trb);
+struct xhci_segment *trb_in_td(struct xhci_segment *start_seg,
+		union xhci_trb *start_trb, union xhci_trb *end_trb,
+		dma_addr_t suspect_dma);
 void xhci_ring_cmd_db(struct xhci_hcd *xhci);
 void *xhci_setup_one_noop(struct xhci_hcd *xhci);
 void xhci_handle_event(struct xhci_hcd *xhci);